This invention relates to gas turbine engines. In particular it concerns a vectorable nozzle mounting for a gas turbine engine for a vertical and short take off and landing aircraft.
In the field of vertical and short take-off and landing aircraft gas turbines are often adapted to provide thrust for both normal wing-borne flight and for lift. This is achieved using vectorable nozzles for changing the direction of the engine thrust. For stability and ease of aircraft control an existing engine of this type employs an arrangement which uses four side mounted nozzles which can be rotated on simple bearings through an angle of over ninety degrees. Two of the nozzles are located forward of the aircraft centre of gravity on port and starboard sides and receive air from the engine compressor. The other two nozzles are located rearward of the centre of gravity on port and starboard sides and receive exhaust gas from the turbine section.
The absence of a conventional axial jet pipe in the basic arrangement enables the rear structure of the engine to incorporate a permanent transverse portion which acts as a gas deflector and strengthens the structure with respect to torsional loads. The rearward pair of nozzles can then be carried by the engine casing which greatly eases problems of sealing the nozzles against hot gas leakage. In a development of this type of arrangement which incorporates an axial jet pipe the transverse portion of the rear structure no longer exists and the torsional loading of the rear nozzles can no longer be tolerated. The nozzles can be carried by the airframe in which case a solution must be found to the difficulty of controlling hot gas leakage from means connecting the engine to the nozzles.
Accordingly it is an object of the present invention to provide a vectorable nozzle arrangement for a gas turbine engine installation in a vertical and short take-off and landing aircraft.